This is so confusing! My DMM measures literally 10mV across its internal 10megohm shunt from (off) anode to ground, which means that the anode is truly OFF... My DMM reports infinite resistance from cathode to ground when it's set to off... Everything seems to be working perfectly!
As a possibly related side note, one of the tubes is slightly brighter than the other, even though their sustaining voltages are within a quarter of a volt of each other and their anode resistors are within 500 ohms. Could this mean anything? On Feb 7, 4:28 pm, will <[email protected]> wrote: > Yeah, I tried that but with a different base-HV resistor I think. It > works just like mine. > > On Feb 7, 1:27 pm, "MrNixie (UK)" <[email protected]> > wrote: > > > > > > > > > Hmm, so i ain't so smart at uploading images! try again... > > >https://docs.google.com/leaf?id=0B3KTZNOahiFEZGY5NGJmMWUtNDE5Mi00NTgz... > > > (but basically, it is a very similar idea to David Forbes Anode > > drivers). > > > LW > > > On Feb 6, 5:39 pm, will <[email protected]> wrote: > > > > Also, as for current leakage, remember that my DMM literally shows > > > like 6mV from anode to ground when the anode is "off", but then for > > > some reason whenever the "7" on the other tube lights up, the anode > > > voltage shoots up, and the same thing happens to a smaller extent with > > > the decimal points. > > > > On Feb 6, 11:15 am, will <[email protected]> wrote: > > > > > Hey MrNixie, I can't seem to access your link. > > > > And indeed, now is a time when I find myself wishing for a good scope. > > > > I'm trying to contact a guy on craigslist right now for one. > > > > I was able to switch my MOSFET pretty well with a totem-pole assembly > > > > (two 100 ohm resistors connected to PNP and NPN transistors, both > > > > joined at the emitters and connected directly to the gate of the > > > > MOSFET). So yes, two resistors and two transistors, but I've already > > > > gone and used them. BTW, I'm actually using an IRF730 in my circuit, I > > > > saved the IRF740 in case I needed to switch a bigger load. > > > > > On Feb 6, 5:40 am, "MrNixie (UK)" <[email protected]> > > > > wrote: > > > > > > Will, This is the point (in case you hadn't noticed!) when a 'scope > > > > > comes in real handy! You really want to pursue that - I use mine a lot > > > > > for fault finding my designs! It will pay for itself in your time, > > > > > Teach you loads and reduce frustrations. > > > > > > I think your issue is not an AC (i.e. transistors not switching off in > > > > > time) issue, but a DC (leakage currents) one. I might suggest a > > > > > different arrangement for your anode drivers, tho. > > > > > > This is my own tried and tested arrangement: > > > > > >https://docs.google.com/leaf?id=0B3KTZNOahiFEZGY5NGJmMWUtNDE5Mi00NTgz... > > > > > > (i hope you can see that?) > > > > > > Also, I can save you at least two resistors and two transistors in > > > > > your HT power supply. Junk that crappy old chestnut of a FET IRF740 > > > > > (pah!) and get a decent low Vgs one from the likes of Toshiba 2SK3562, > > > > > to name but one. These switch cleanly with a gate voltage of 5V, > > > > > supplied STRAIGHT from your controller IC. > > > > > > Laurence -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
